1. Field of the Invention
The invention relates to novel polishing slurry compositions for chemical mechanical and polishing metallic thin films, and particularly, to improved polishing slurry compositions with increased suspension stability of solid abrasives for chemical mechanical polishing metallic thin films and to the use of such polishing slurry formulations in chemical mechanical polishing of metallic thin films, especially metallic thin films deposited on semiconductor substrates.
2. Description of the Prior Art
In an multiple in-line manufacture process of ultra integrated circuits, a dielectric outer layer having a fluctuated surface is generally formed due to surface fluctuation of the metal on the surface of the chip, thereby influencing the precision and resolution of image transfer. A flattened dielectric layer is favored for subsequent in-line manufacturing of the metal and thus a more precise conductor pattern is transferred. Heretofore, only chemical mechanical polishing can provide wholly flattening of the dielectric layer. U.S. Pat. No. 5,209,816 to C. Y. Yu et al. discloses slurry compositions comprising hydrogen peroxide, water, phosphoric acid and solid abrasives, which, in a mixed chemical and mechanical manner, oxidizes surface metallic aluminum with hydrogen peroxide to form an aluminum oxide layer, and meanwhile, mechanical polishing and phosphoric acid etching the aluminum oxide layer. A continuous agitation must be maintained in the polishing process using this slurry compositions. However, it still can not prevent settling of alumina power and/or unstable distribution uniformity, thereby resulting in easily scratching and damage of the chips to be polished.